<div dir="ltr"><div>Hi</div><div><br></div><div>apologies for the stupid question.  I was reviewing some teaching material and looked at the following Scheme (form SICP) code about "streams".</div><div><br></div><div>

<span style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">(define (integral integrand initial-value dt)</span><span style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none"><br>  (define int</span><br style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">    (cons-stream initial-value</span><br style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">                 (add-streams (scale-stream integrand dt)</span><br style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">                              int)))</span><br style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="color:rgb(0,0,0);font-family:monospace;font-size:medium;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">  int)</span>

</div><div><br></div><div>The question is how you'd rendered it in Common Lisp or how you would provide some macrology to mimic the inner <span style="font-family:monospace">define</span>.  I know this has been asked before...  I am sure somebody knows the answer.</div><div><br></div><div>All the best<br></div><div><br></div><div>-- <br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Marco Antoniotti, Professor                           tel. +39 - 02 64 48 79 01<br>DISCo, Università Milano Bicocca U14 2043   <a href="http://dcb.disco.unimib.it" target="_blank">http://dcb.disco.unimib.it</a><br>Viale Sarca 336<br>I-20126 Milan (MI) ITALY</div></div></div></div>